Pigmented cellulose fiber



stocks containing around 4 or 5 or 6% of fibers (dry basis) the amount of calcium chloride is advantageously such as to form a solution of Y e. g. 13% or higher or up to 15 to 20% rormore,

and saturated calcium chloride solutions can be used. With more dilute pulps containing e. g., around 1% or 2% of fibers (dry basis) a more dilute calcium chloride solution can be used, e. g., a solution containing 5% or more` calcium chloride or more advantageously a solution containing around or more calcium chloride, with prolonged mechanical treatment orrbeating to effect swelling hydration, and gelatinization of the pulp fibers.

Y With strong calcium chloride solutions, e. g., around 13 to 20%, a profound modiiication. of the cellulosic bers takes place in a short period of time, e. g., 5 to 10 or 15 minutes, with proper agitation. The fibers become moreV or lessV gelatinous and transparent in appearance. With more .dilute calcium chloride, solutions prolonged beating-of the pulp in a beater is advantageous toY promote the hydrating and gelatinizing action and also to convert the pulp into a refinedl pulp.

Instead of adding dry calcium chloride to an f ordinary pulp containing a small percentage of fibers, the treatment can be carried outv by adding drypulp stock (chemical, semi-chemical or mechanical pulp) to a more dilute aqueous solution of. calcium chloride, advantageouslyl a 10% solution, and with beating or refining of the pulp to promote the action of the calcium chloride on the bers Aand to bring about the swelling and hydrating and gelatinizing action with resulting, incorporation of a Vconsiderable amount of the calcium chloride within the fibers aswell as on and around them. This method of treating Vdry pulp with an aqueous solution of calcium vchloride lis more fully described in @1y-'Companion application Serial No. 15,509, now

Patent-No. 2,583,548 issued January 29, 1952,

After such treatment of the pulp fibers with calcium chloride theY stock is treated with a solution of a solublev salt such as sodium carbonate (soda ash). or sodium borate, e. g., inA

soluble salt is advantageously slightly in excessA Y of that required to react with all of the calcium chloride, but with groundwood fibers care should in general be Vtaken to avoid any excess of theY alkali salt which would darken or otherwise affect"thestock, and with such stock the calcium .chloride and sodium carbonate lare used in exact-@reacting.proportions or with a slight excess 'ffg'calcium chloride. f

Theresltingtreated*and pigmented stock iS highlylhydated Vandin general has much lessstrength than' the untreated stock but it carries 4 the precipitated pigment distributed throughoutl the hydrated stock While pigment is also precipitated on the hydrated stock and in the water in which the stock is suspended.

This specially treated and modied ,stock is highly pigmented. The amount of pigment is in excess of the weight of the stock treated (dry basis) and particularly advantageous products are made by incorporating an amount of pigment which'is twice the weight of the fibers or three times the weight of the fibers or even four or ve times thevweight of the fibers or more, as illustrated, for example, in Example l, where the weight of the pigment is about 7.7 times the weight of the fibers, and in Example 2, where the weight of the pigments is about sixteen times the weight of the fibers.

The stock after treatment with the calcium chloride and with the soluble sodium salt will contain sodium chloride in solution. A large part of this salt will be removed when the fibrous stock is filtered or the main part of the Water is separated from it but it is advantageous to wash the treated stock to effect more or less complete removal of the sodium chloride or the greater.

part of it before the pigmented stock is dried. The washing of the treated stock can be carried out by decantation or by washing in pulp washers with replacement of the sodium chloride solution ment during the washing operation.

This washed stock will contain the pigmented:

bers or fibrous pigment withra relatively large amount of water. To produce the dry iibrous pigment or pigmented fibers this stock is freedA from the main portion of its water by filtering much water as possible. x And the resulting wetv or passing over a screen and advantageously in the form of a continuous sheet'from which most of the water is drained or sucked by vacuumV or by passing through pressure rolls Vto squeeze out as pulp is then 'driedvunder regulated conditions to form the dry product.

It is important, for producing products which` can be readily rehydrated and reconverted into pulp form with water, to lavoid excessive drying and the production of a bone dry product,which is less valuable as a fibrous pigment. The drying can, however, be carried out rapidly by passing wet pigmented fibers through a continuous drierv in sheet form and drying to the point where it A too long a time for practical operations.

still contains va small amount of water, e. g., around 5 to 10% more or less based on the fibrous content of the pigmentedv fibers. The product can also be air-.dried but this will ordinarily takev Ordinary drying rolls can be used with a limited time of contact of the continuous pigmented fiber sheet with the hot rolls to avoid excessive heating and drying. Thev wet fibrous pigmentor pig-A g. mented fibers can also Ybe broken up into lumps orV into small pieces before drying. `The dried' product can-also be Vbroken up into lumps or pieces'or into coarse powder form orvthe dried,v product can be formed into rolls or into 'laps *forstorage and shipment.

.This new dry fibrous pigment or pigmented fibrous product will contain the nely divided precipitated pigment in amount exceeding the" weight ofthe vfibers treated and advantagecusly'- l .in amount two or three or four times the weight of thebers or even more.

-This new bro -pigmentis a valuable pigment 'l 5; foe use; in paese makin@ freren gourmet- If-the oelluloo more@ l ae fr; 1&1 u; o fithoeraulm b ei stir d to ins `e thorough distribution of the ca e oiiemfohigrigeeensfihseeimo whsfipsrs@ r @l .1, @d

l "smi eereo'xefimif tofthefbeetei end eubleotedf.- toi f or; to the; bes-tothe; on@ of; th, f -z u@ treatment. It can be rst rehydmtemb hr1 tlleOdiumy e: it with water and forming it into gigmtged 1 qeu@ E* mtg fibrous;eulpfeud. esisoihfthsiorm 12u-lp f place mi' a I Olge j/ dryn bers,i .ff Eaamzzle., f2 .-A13 alphaeollulose; hule- ,lgteel M narod; b y heatmgm, mefbeatelz- @tuev/2% sistenoy and to, 4310i partsof nosultlnefs i containing 15 palzfsofalnhefoolluloseft is added 315A, parts. of oaloiinmtcmori continued stirring; or: agitation, infthobek described-in Example I and thenifmrtsroff sodium.. carbonate sadlE yare2=1f1de$1f he, form of a, m96, solutiontaudthe;groem-is @Re tinuedasgn- Exampleg1li' GQ, '1 -The products of 'the alloue exampleeooutaiu manutnnes,asmuohopiemontasg-heu.(dugbassistwith.y renedbersthe bers max haxle @Rmb appearanceoneriudine.y Althoughfthedrytpmdefu otis ,.ma.de upt-manly-fof,gigmentitfi nenrtheless,r brpusm charactengetgimngqi sommi-#hit brous structure of'the treated-11h ebutoQxr-e taining;l a. Ilaureeafmounttofureoipetedo Wthiufndon, and around metfibers;` Exmple 2, about 244A parts of calcumfaxbgmjg., 795. resul ing will be produced from 315 parts of dry calcium" ;.ohlonideueechloride., spv-that-thecmbouutepigment is about h1 16 times the weight ofthe dry pulp (15 parts).

Example-$51kpastoor-emmne@ gulp oontainng 3.5% of fibers (dry basis) are treated by 7 5?.`

centaine relativen smell percentage ern-bef and? anr amount fofene precipitatedpiglnfnt 'sevefal times the Yweight of the ber. Sucli'p'ro'ducts are valuable brous pigments which can be adm'ixed with water andfreconverted*into-the form "of ai brous pigment stock or pulp'. Altho'tiglthe" brous content-fis' relatively sn'ialL-l it nevertheless has a profound modifyingv "effect in 'holding-fthe' nely divided precipitated calcium carbonate'i'n- Y a condition'which minimizes'lossof pigment and enables thepigment 'to'be4 readily incorporated* withordinary paper pulp stools.V 'i f' 'f' i' -While it is possible by using a l'stock of higher concentration of bers and a-le'ssv'exces's vofcal-` cium chloride 'to produce pigmented bers wh` contain approximately equal parts byV weight ber and pigment, it is more advantagof produce morehighly-'pigmented'berswhch 'co tain at least twice as much Apigment as ber and evenV more advantageous `for many purposes tov produce 'pigmented bers containing'thr'ee or four or ve times as much pigment 'as'ber" or'v higher percentages. x .3 The new fibrous Vpigments or` pigmentedi4 bers can 'similarly' Ybe made with-barium and 'Vzinc 'pig'- ments, bythe addition of dry -piilp t'o a"solutivzin V of barium chloride landai-'nc chloi'deor'by Kac'cingv drybarium-chloridel'offry zinc chloride to an aqueous pulpAwith ymechanical treatment 'when required to effect swelling and hydrating'andfge latinizing ofthe pulp bers in the` bariuniclilride I or in-the zinc chloridesolutionfollowed by preljI cipitation of the insoluble barium orzine p igf-vV` ment by thezaddition of a soluble salt ysuch as so-ll diuin 'sulfate or alum` (aluminumf-sulfate.) other soluble'sulfate', or 'byfaiidin'g l bonate or other soluble zcarbc' nate,"etc.-to precipi-'p tate' insoluble barium sulfate or Zinc sulfateor a" mixture of barium sulfate? and aluminum hydrate' or bariumJ orzinc carbonate o r zincf'silica'te "or" and around the cellulosic bers;

Water -toform a' pulp which can then be used for admi'xture'ewi'th untreated 'pulp or paper stock togivea lpig'smented paper stock and paper.

'if Suchliighlypigmented bers containing baribm orzinc pigments, after drying and converte ing i'rit pulpA form,aswell as before drying land wbilein'a'pulp form, 'canbe'used for admixture with ordinarypaper stock to supply fibrous pigment {theretoas vdescribedin connection with the brous #pigments containing insoluble calcium pigments '-in my'prior applicationsSerial Nos. 6644251a'1d 666,199. 'e Y l.- Highly pigmented cellulosic pulp comprising the dried residue of swollenfhydrated and gelatinizedcellulosicbers and an'amount of nelydivdedi'pigment inexcess of the dry weight of'the ber'sffand Lnot exceeding about 316 :times the weight "of the fibers, "thel pigment being selected from the class which, consists'- of precipitated inorganic salts of calcium, Vbariumy and zinc, the finely-dividedV pigment being largely within the cellulosic 4bers but also' on vand around said bers, the finely-divided4v pigment within Y the bers hayingA been*Y precipitated in situ therein by reactionof one soluble salt with aV second soluble 4salt while the second-soluble salt is Within the bers while they are in a swollen,l yhydrated andv fg'elatinized state', said pigment materiall Y zinc hydroxide,etc. largely within andalsofo'n'i scribed in connection' with calcium *chloride byfe4 addig dry barium f'clloride or'Y dry' zinfc'l'ilorid to a`brous pulp or by`adding dryvpulp'to the barium chloride or zinc chloride soltion Withmechanical'treatment whenneeded to eiect the' hydrating and swelling -and gelatinixzingl 'of' the bers so that a minimum'of free water is present' around the' gelatinized bersand by thenY precipi tating--the insoluble'barium oryzincr pigment byu adding the solubleprecipitating Asalt to'ftle'felat-'- iniz'eds'tock.V "ff-' Il The amount offinsoluble barium 'ore'zincipig-"" ment, as well as the amountof` insoluble .calciui'r'rx pigment, will exceed the'dry weight' ofthe'be'rs and-'willadvantageously be two or three or four v or more times the weight `of the bers' and 'the pigments willv be largely containedl in a "fineprecipitated state within the vbers as we1l`as`on and; around the bers. Y "#5" e The highly pigmented bers containing.r "thelin' soluble barium or zinc pigments when produced'j in` pulp form can be dried under 'regulated `Yconi ditions Y to give dry fibrous pigments" which can be shipped and stored and used by admixin`g-"'w'ith'4 forming-` a: Ypulp-like mas'son admixture .with

water.'4 'r I r Y v n 2. `Iibrous lpigments s uchas dened in claim' l in which ;theV ellulosic bers are 'chemical cellue 10st pulp bers:

Y 3. VFipreue pigments sueas; defined in daim 1v infwhichrthe bers are groundwood bers.

1i..v Fibrous pigments such asfdenedin claiml` injwl'ich 'the' pigment is more than twice the weigllt'of the bers; Y

"15. lFibrous'pigments such as dened in claim 1 in'V which the`1igmentv is more than three times th'e weight of the bers.

46.librous pigments such as dened in claim-1y isvmore thanifour times the' in Whichthe pigment "fli'bro'us' pigments such as dened-in claim 1 in vwhich the pigment is a calcium carbonate pigmentjprecipitated vbythe reaction of calcium' chlorideand sodium carbonate. 1

8, Fibrcus pigments such as dened in'claimy 1 in'fwhich the pigmentis a calcium carbonate pigment precipitated- 'by the'v reaction of calcium:

amount more chloride and sodium carbonate, in

than'twicetheweight o f the bers.

'1 -9'. Fibreus' pigments such as'dened in claim 1 lnfwhc'h the pigment isa calcium carbonate pigment precipitated by vthe reaction of4 calcium chloride and' sodium'carbonate, in amount more than three times the weightgof the bers.

1Q. Eibrous pigments suchas dened in claim 1 in which the pigment is a calcium carbonate pigmentprecipitated"by' the reaction of icalcium chloride andI sodium carbonate, in Aamount more thanr vfour timest'he weight of the bers.

l 1;1.V vrllii'brous pigments `'such as denedin claim 1 mel-whichthefpigmep is a precipitated barium' compound pigment" 121 {Fibrous Vpigments vsuch as denedjin claim l1 I in whichthe pigment is a precipitated zinc com'- LUTTQN CRAIG.V

9 10 REFERENCES CITED` FOREIGN PATENTS The following references are of record in the Number Country Date file of this patent: 404 Great Britain of 1869 UNITED STATES PATENTS 262 Great Britain 0f 1873 5 151,381 Great Britain Sept. 27, 1920 Number Name Date '348,958 Flegle sept. 14, 1886 OTHER REFERENCES 354,477 JuSt et al- Dec. 14, 1886 Lottermoser et a1., Kolloid-Zetscrft, vol. 57J 2,080,437 RaftOn May 18, 1937 1931, pgs. 206-208, 211-212, 216 and 221. 2,189,832 Rafton Feb. 13, 1940 lo An Introduction to the Chemistry of Cellulose," Marsh & Wood, 1938, pgs. '73, 77-78. 

1. HIGHLY PIGMENTED CELLULOSIC PULP COMPRISING THE DRIED RESIDUE OF SWOLLEN, HYDRATED AND GELATINIZED CELLULOSIC FIBERS AND AN AMOUNT OF FINELYDIVIDED PIGMENT IN EXCESS OF THE DRY WEIGHT OF THE FIBERS, AND NOT EXCEEDING ABOUT 16 TIMES THE WEIGHT OF THE FIBERS, THE PIGMENT BEING SELECTED FROM THE CLASS WHICH CONSISTS OF PRECIPITATED INORGANIC SALTS OF CALCIUM, BARIUM AND ZINC, THE FINELY-DIVIDED PIGMENT BEING LARGELY WITHIN THE CELLULOSIC FIBERS BUT ALSO ON AND AROUND SAID FIBERS, THE FINELY-DIVIDED PIGMENT WITHIN THE FIBERS HAVING BEEN PRECIPITATED IN SITU THEREIN BY REACTION OF ONE SOLUBLE SALT WITH A SECOND SOLUBLE SALT WHILE THE SECOND SOLUBLE SALT IS WITHIN THE FIBERS WHILE THEY ARE IN A SWOLLEN HYDRATED AND GELATINIZED STATE, SAID PIGMENT MATERIAL FORMING A PULP-LIKE MASS ON ADMIXTURE WITH WATER. 